Investigation of Propagation Characteristics of Twisted Hollow Waveguides for Particle Accelerator Applications

摘要: A new class of accelerating structures employing a uniformly twisted waveguide is investigated. Twisted waveguides various cross-sectional geometries are considered and analyzed. It shown that such can support waves travel at speed slower than the light c. The slow-wave properties interest because these electromagnetic fields be used in applications as electron traveling wave tubes linear particle accelerators. Since there no exact closed form solution for within or cavity, several previously proposed approximate methods examined, more effcient approaches developed. found existing perturbation theory yield adequate results slowly structures; however, our efforts here geared toward analyzing rapidly using modifed finite difference specially suited structures. Although method handle general structures, three particular cross sections selected representative cases careful analysis. First, rectangular cavity analyzed reference case. This its shape simple already gives good slow twists rates. Secondly, symmetrically notchedmore » circular section investigated, since longitudinal comparable to well known disk-loaded (used many practical accelerator designs, including SLAC). Finally, "dumbbell" shaped similarity well-known TESLA-type which great importance wide acceptance superconducting cavity. To validate developed extensive simulations, newly numerical models compared commercial codes. Also, prototypes basic shapes discussed previously. Bench measurements performed on prototype cavities evaluate dispersion by measuring field distribution along cavities. measurement simulations theoretical results, agreement shown. Once validated, design with specific phase velocities performance.« less